A positron moves in a circular path of radius R due to a uniform magnetic field of strength B applied perpendicular to the plane of the circle. If B is varied, which of the following best represents a graph of the kinetic energy of the positron as a function of B so that the positron maintains the same radius R.
The Attempt at a Solution
KE = 1/2MV^2
Rearranging first equation, RqvB =mv^2, then multiply each side by 2
2RqvB = KE
Here i thought that KE is proportional to B, but v remains a variable that depends on KE. How do create a relationship between B and KE?